Superfluid density of a pseudogapped superconductor near SIT

TL;DR

This paper investigates the critical behavior of superfluid density in disordered superconductors near the superconductor-insulator transition, revealing an unusual scaling relation that aligns with recent experimental findings.

Contribution

It demonstrates that superconductors with preformed pairs exhibit a unique scaling relation between superfluid density and spectral gap near the transition, contrasting with conventional superconductors.

Findings

Superfluid density scales as the square of the spectral gap near SIT

Unusual scaling relation observed in superconductors with preformed pairs

Experimental data supports the theoretical prediction

Abstract

We analyze critical behavior of superfluid density $\rho_s$ in strongly disordered superconductors near superconductor-insulator transition and compare it with the behavior of the spectral gap $\Delta$ for collective excitations. We show that in contrast to conventional superconductors, the superconductors with preformed pairs display unusual scaling relation $\rho_s \propto \Delta^2$ close to superconductor-insulator transition. This relation have been reported in very recent experiments.